SCOURING  OP  WOOL  IN  BELGIUM 
GP3AT  BRITAIN  AND  GERMANY 


UNIVERSITY  OF  CALIFORNIA 
AT  LOS  ANGELES 


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SCOURING  OF  WOOL  IN  BELGIUM,  GERMANY,  AND 
GREAT  BRITAIN. 


BELGIUM. 

REPORT  Of  CONSUL  ROBERTSON. 

Wool-washing  proper  is  divided  into  three  processes. 

First  process. — The  wool  is  first  put  into  large  cone-shaped  tubs  (small 
end  down)  with  holes  in  the  bottom.  Cold  water  is  then  poured  on  until 
the  tubs  are  full,  and  allowed  to  filter  through  the  wool,  which  is  left  in 
the  tubs  until  the  water  ceases  to  run.  This  water,  escaping  through 
the  holes  in  the  bottom  of  the  tub,  carries  with  it  most  of  the  grease 
from  the  wool,  and  is  collected  in  reservoirs,  from  which  it  is  taken  in 
reservoir  wagons  to  an  establishment,  there  being  but  one  in  Verviers, 
which  collects  from  all  the  wool-washers,  where  it  is  boiled  down  to 
evaporate  the  water.  The  solid  product  thus  obtained  is  in  furnaces 
turned  into  potash.  Illustration  No.  1  shows  another  machine  which  is 
by  some  substituted  for  the  cone-shaped  tubs  in  this  first  process,  and 
which  is  arranged  to  automatically  transfer  the  wool  to  the  next  set  of 
tubs  for  second  process. 

Second  process. — The  wool  is  next  put  into  a  tub  or  trough,  about  5 
feet  wide,  10  feet  long,  and  perhaps  1.8  inches  to  2  feet  deep,  of  hot  water 
(about  100°  Fahr.).  This  bath  contains  soda  and  a  soap  made  of  oleine. 
It  is  here  stirred  and  passed  along  through  a  series  of  two  or  three  of 
these  baths  (troughs)  by  revolving  rakes  with  long  curved  iron  teeth 
(see  Illustration  No.  2)  into  the  rinsers. 

Third  process. — Consists  of  a  rinsing  bath  of  cold  water,  the  purest 
obtainable,  and  is  accomplished  in  the  same  manner  as  the  second  bath, 
in  a  tub  or  trough,  stirred  and  thrown  out  automatically.  (See  Illustra- 
tion No.  3.) 

In  these  three  processes  the  wool  loses  from  one-third  to  three-quar- 
ters of  its  weight,  according  to  kind  and  quality. 

The  rinsing  water,  which  is  continually  chau'ging,  and  issues  from  the 
tub  comparatively  clean,  is  allowed  to  run  directly  into  the  river;  but 
the  water  from  the  aecond  bath  (second  process)  is  taken  by  a  collecting 
canal  to  two  large  reservoirs,  in  the  first  of  which  it  remains  about  twenty- 
four  hours,  it  is  then  passed  to  the  second  to  remain  an  equal  length 
of  time.  This  is  in  accordance  with  police  regulations.  The  sediment 
remaining  in  these  reservoirs  is  taken  out  from  time  to  time,  and  is  used 
for  agricultural  purposes,  making,  it  is  said,  a  very  rich  fertilizer. 

The  stream,  the  Vesdre,  into  which  all  this  water  eventually  finds  its 
way  is  nevertheless  a  most  filthy  one,  and  no  life  can  exist  in  it,  though 
its  volume  is  not  sufficient  to  materially  contaminate  the  river  Meuse, 
into  which  it  empties. 

3 


145803 


4  SCOURING    OF    WOOL. 

From  the  rinsing  bath  the  wool  is  put  into  copper  vessels  about  2£ 
feet  in  diameter,  and  perhaps  the  same  depth,  the  sides  and  bottoms  of 
which  are  perforated  like  a  sieve.  These  vessels  hold  from  30  to  40 
pounds  of  wool.  They  are  made  to  revolve  with  great  velocity  (1,000 
turns  per  minute)  and  the  water  is  thrown  out,  escaping  through  the 
sides  and  bottoms,  so  that  the  wool  when  removed  is  comparatively  dry; 
quite  so  to  the  touch. 

This  operation  requires  from  two  to  three  minutes,  and  the  drying  is 
then  completed  on  racks  in  lofts,  which  are  heated  by  steam  to  a  tem- 
perature of  about  100°  Fahr. 

The  foreign  substances  contained  in  the  wool,  such  as  burs,  &c.,  are 
combed  out  by  machinery  after  the  wool  has  been,  when  necessary, 
passed  through  a  series  of  corrugated  rollers  to  break  them  (i.  e.,  the 
burs,  &c.)  up.  The  combings  are  then  treated  in  a  bath  containing 
sulphuric  acid  (the  water  from  which  is  also  run  into  the  settling  reser- 
voirs), rinsed  in  pure  cold  water,  and  then  dried  in  kilns  at  an  average 
temperature  of  245°  Fahr.  This  removes  whatever  is  left  of  the  sulphur, 
and  also  burns  up  any  foreign  substances  still  remaining. 

G.  D.  ROBERTSON, 

Consul. 

UNITED  STATES  CONSULATE, 

Liege,  Belgium,  November  28,  1885. 


GERMANY. 

REPORT  OF  CONSUL  DITHMAR. 

\ 

Eemoval  of  all  foreign  substances  from  the  wool  usually  precedes  the 
scouring.  This  preliminary  cleaning  is  done  by  hand-picking,  by  beat- 
ing, and  by  machinery  constructed  for  the  purpose.  . 

The  factory  cleaning,  to  which  all  wools  are  subjected,  consists  of  three 
distinct  operations:  (1)  Removal  of  the  grease;  (2)  thorough  washing; 
and  (3)  drying  the  wool.  The  methods  by  which  these  objects  are  ac- 
complished differ  according  as  the  wool. is  long  or  short  staple. 

The  long  staple  spinner  in  the  scouring  process  seeks  to  soften  the 
wool  and  make  it  pliable.  It  is  placed  in  water  heated  to  168°  Fahr., 
and  to  which  6  pounds  of  soap  is  added  to  every  hundredweight  of 
wool,  and  sometimes  also  a  quantity  of  soda.  Alter  the  wool  has  re- 
mained for  some  time  in  this  soapy  bath  it  is  taken  out  and  passed 
through  rollers,  again  thoroughly  washed  in  soapsuds,  and  after  being 
a  second  time  passed  through  rollers  is  immersed  in  clean  water  heated 
to  140°  Fahr.  The  wool  being  thus  thoroughly  cleansed  of  all  impuri- 
ties, is  passed  through  rollers  a  third  time,  and  is  now,  although  not 
quite  dry  and  still  warm,  ready  for  the  other  processes  which  precede 
the  spinning. 

Short  staple  is  soaked  in  ammonia,  usually  made  of  one  part  decom- 
posed urine  to  two  parts  water,  and  heated  to  140°  Fahr.  In  this  bath 
the  wool  is  placed,  loosely  packed  in  wicker  or  wire  baskets,  and  moved 
backward  and  forward  for  about  fifteen  minutes,  and  when  it  has  be- 
come somewhat  dry  and  cool,  after  being  taken  out,  is  rinsed  in  clear 
running  water,  and  is  then  placed  on  hurdles  to  dry. 

To  rid  the  wool  of  the  harshness  caused  by  the  scouring  it  is  greased 
with  olive  oil  in  the  proportion  of  1  pound  of  oil  to  8  or  10  pounds  of 


SCOURING    OF    WOOL.  5 

wool.     In  some  places  goose-grease  or  fresh  unsalted  butter  is  used  in- 
stead of  oil. 

Wool  that  has  been  stored  five  or  six  months  after  clipping  and  is 
well  dried  contains  less  grease  and  cleans  more  readily  than  fresher 
wool. 

The  loss  of  wool  resulting  from  the  scouring  is  estimated  at  2  to  7  per 
cent.,  according  to  the  strength  of  the  lyes  and  the  temperature  of  the 
water. 

The  grease  resulting  from  the  wool  washing  is  put  to  various  uses, 
principally  for  making  axle-grease  and  cheap  soaps.  From  the  liquid 
remaining,  potash  is  sometimes  manufactured  ;  sometimes  it  serves  for 
irrigation.  When  the  potash  has  been  extracted,  the  remainder,  like 
the  obnoxious  fluids  from  sugar  factories,  is  filtered  and  allowed  to  take 
its  course  to  the  nearest  stream.  The  general  law  against  the  pollution 
of  streams  by  factory  offal  includes  wool-washing  as  well  as  dyeing  and 
sugar-making. 

HENRY  DITHMAR, 

Consul. 

UNITED  STATES  CONSULATE, 

Breslau,  December  8, 1885. 


GREAT  BRITAIN. 

HE  PORT  BY  CONSUL  GEINNELL. 

Consul  William  F.  Grinnell,  of  Bradford,  transmits  to  the  Department, 
under  date  December  4, 1885,  the  following  letters,  courteously  written 
in  reply  to  certain  inquiries  addressed  by  him  to  the  writers: 

BRADFORD,  November  10,  1885. 

DKAR  SIR  :  In  reply  to  yonr  favor  of  the  9th  instant,  we  have  much  pleasure  in  sup- 
plying the  information  you  ask  for,  respecting  wool-washing,  &c. 

Before  being  submitted  to  any  process  of  manufacture,  all  wools  are  washed  or 
scoured  in  a  solution  of  soft  soap  and  hot  water,  technically  called  "  suds."  When 
the  cleansing  qualities  of  this  solution  are  exhausted,  the  waste  or  dirty  water  is  con- 
veyed into  a  cistern,  and,  while  still  warm,  a  certain  quantity  of  oil  of  vitriol  (B. 
O.  V.)  is  introduced,  by  which  the  solid  matter  and  grease  are  precipitated. 

After  standing  for  a  few  hours,  for  the  separation  to  be  completed,  the  clear  water 
is  run  off  into  the  public  sewer. 

The  solid  matter,  while  still  in  a  semi-liquid  condition,  is  then  run  off  into  filter- 
ing frames  lined  with  cocoanut  matting,  through  which  the  remaining  water  perco- 
lates and  runs  into  the  public  sewer.  Thus  there  is  left  in  the  frame  the  dirt  and  fatty 
matter  in  the  form  of  a  thick  paste,  called  "  magma." 

The  magma  is  next  put  into  canvas  bags  or  wrappers,  and  placed  in  a  steam-heated 
hydraulic  press,  where  it  undergoes  a  process  similar  to  that  of  ordinary  seed-crush- 
ing. The  fatty  matter,  both  from  the  wool  and  soap  used  in  the  washing  now  oozes 
ou;  in  the  form  of  a  brown  liquid,  which  is  run  into  casks,  and,  when  cold,  forms  the 
substance  known  in  the  trade  as  "  brown  grease."  This  grease  is  used  for  a  variety 
of  purposes,  such  as  the  lubricating  of  axles,  &c.;  but  the  bulk  of  it  is  bleached  and 
made  into  what  are  called  wax  candles,  vestas,  &c.  In  this  latter  proess  an  oil  is  ob- 
tained which  is  largely  used  for  lubricating  shafting  and  the  like. 

The  solid  matter  remaining  in  the  canvas  wrappers  in  the  hydraulic  press  after 
the  grease  has  been  squeezed  out  is  used  by  the  farmers  as  manure. 

Any  further  information,  so  far  as  we  may  be  able,  we  shall  at  all  times  most  will- 
ingly give  you,  and  in  the  meantime  we  remain, 
Yours,  very  respectfully, 

THOS.  AMBLER  &  SONS. 

WILLIAM  F.  GRINNKLL,  Esq., 

United  States  Consul,  Bradford. 


6  SCOURING    OF   WOOL. 

Report  from  Messrs.  William  Ramsden  $•  Co.,  Bradford,  to  William  F.  Grinntll,  United 
States  Consul. 

SCOURIKG   OF   RAW  WOOL. 

From  the  earliest  times  stale  or  putrid  urine  has  beeu  employed  for  scouring  wool, 
but  it  has  now  been  almost  entirely  supplanted  by  soaps,  used  either  alone  or  mixed 
with  potassium  or  sodium  carbonate.  The  active  ingredient  in  stale  urine  is  ainmo'- 
nium  carbonate,  which  is  a  mild  alkali  admirably  suitable  for  the  washing  of  wool; 
but  it  is  too  expensive  for  general  use.  Potash  soap  is  now  almost  universally  employed 
in  wool-scouring.  It  has  been  fully  proved  that  better  results  are  obtained  by  th« 
employment  of  soap  made  with  potash  than  by  one  made  with  soda.  The  most  suit- 
able fatty  matters  to  be  combined  with  the  potash  are  those  in  which  oleic  acid  pre- 
dominates. 

It  is  most  important  that  the  soap  employed  should  be  free  from  caustic  alkalies, 
since  these  bodies  act  very  injuriously  upon  woolen  fiber. 

The  temperature  of  the  washing  liquor  should  not  exceed  100°  Fahr. 

The  usual  method  followed  in  England  is  to  wash  the  wool  successively  in  three 
or  four  tanks.  One  lot  of  wool  is  allowed  to  steep  in  one  of  the  tanks  while  another 
lot  is  passing  through  the  machine.  The  liquor  which  is  in  the  first  tank  has  already 
been  fouled  to  a  certain  extent  in  the  second  and  third  tanks,  and  that  in  the  second 
tank  has  been  previously  used  in  the  third.  The  great  bulk  of  the  grease,  dirt,  &c., 
is  collected  in  tank  No.  1,  and  at  certain  intervals,  varying  according  to  the  nature  of 
th«  wool  which  is  being  cleansed,  the  liquor  is  run  off  into  large  vessels,  where  the 
soapy  matters  are  decomposed  and  the  grease  recovered. 

Tank  No.  1  is  now  filled  with  the  liquor  from  tank  No.  2,  and  the  latter  is  then  iu 
a  similar  manner  charged  with  the  liquor  from  tank  No.  3.  Fresh  soap  solution  i& 
placed  in  the  last  tank  only. 

If  the  wool  is  very  greasy  it  is  usual  to  add  an  alkaline  carbonate,  preferably  potas- 
sium carbonate  (pearlashes),  to  the  liquor  in  the  first  tank,  but  the  other  tanks  (es- 
pecially the  last  bath)  should  contain  only  a  solution  of  neutral  potash  soap.  The 
wool  is  worked  up  with  iron  forks;  and  is  gradually  carried  forward  by  means  of  an 
endless  band  ;  after  leaving  each  tank  it  passes  through  a  pair  of  rollers,  which 
squeeze  out  the  excess  of  soapy  liquor.  The  wool  is  finally  thrown  off  by  a  fan  in  a 
loose,  open  condition. 

In  France  the  wool,  before  scouring,  is  systematically  treated  with  tepid  water,  in 
order  to  remove  a  peculiar  fatty  body  termed  "  suint,"  from  which  a  very  pure  potas- 
sium carbonate  is  obtained.  When  the  liquor  baa  become  of  a  certain  degree  of 
strength  it  is  evaporated  to  dryness  and  the  residue  ignited.  The  organic  fatty  mat- 
ter burns  away  and  potassium  carbonate  remains  in  the  form  of  a  dirty  gray  mass. 
Potassium  carbonate  is  very  soluble  in  water,  and  may  easily  be  separated  from  cer- 
tain impurities  associated  with  it  in  the  ignited  residue. 

Carbon  disulphide  has  been  used  for  the  cleansing  of  wool,  but  although  even  on  a 
large  scale  a  certain  degree  of  success  has  been  attained,  the  method  does  not  appear 
to  have  been  adopted  to  any  great  extent.  It  is  said  that  wool  cleansed  in  this  way 
is  stronger,  and  that  it  will  spin  to  finer  counts  of  yarn  than  the  same  quality  of  wool 
which  has  been  scoured  and  washed  in  the  ordinary  way. 

RECOVERY  OF  THE  GREASE. 

The  waste  liquors  from  the  scouring  tanks  contain  in  solution  the  soap  and  alkalies- 
which  have  been  employed  together  with  the  "sniut"  and  oily  matters  derived  from 
the  wool.  By  the  addition  of  an  acid  to  soap  the  latter  is  decomposed  with  the  form- 
ation of  a  free  fatty  acid  and  an  alkaline  salt.  Thus  when  sulphuric  acid  (oil  of  vit- 
riol) is  added  to  a  solution  of  ordinary  soft  soap,  oleic  acid  rises  to  the  surface  and 
potassium  sulphate  remains  iu  solution. 

The  wash  soap  liquors  are  run  into  large  tanks  or  pits,  and  a  slight  excess  of  sul- 
phuric (common  chamber  acid)  is  added.  The  liquid  has  a  broken,  curdy  appearance, 
and  after  thorough  agitation  it  is  allowed  to  stand  until  the  crude  fatty  matters  have 
risen  to  the  surface.  The  under  liquor,  containing  in  solution  sulphates  of  the  alka- 
lies (together  with  any  glycerine  present  in  the  soap  used),  is  allowed  to  run  away. 
The  "magma,"  or  fatty  matter,  is  collected,  and  drained  in  filters  made  of  coarse 
cocoanut  matting.  The  separation  of  the  fatty  matters  is  accelerated  by  heating  the 
mixture  of  soap  liquor  and  sulphuric  acid  in  large  wooden  cisterns  by  means  of  steam. 
The  "magma,"  containing  grease,  but  associated  with  much  refuse,  is  placed  in  bags 
and  introduced  into  a  steam  press.  Steam  is  admitted  and  a  gradually  increasing 
pressure  applied.  The  fat  melts  and  runs  out  along  with  water  into  a  tank,  from 
which  it  is  afterwards  pumped  into  a  purifying  vessel.  The  fat  or  grease  is  boiled 
for  some  time  in  this  vessel  with  a  small  quantity  of  diluted  sulphuric  acid,  which. 


SCOURING    OF    WOOL.  7 

destroys  certain  impurities.  After  running  off  the  aqueous  acid  solution  the  grease 
is  transferred  into  casks.  On  cooling  it  solidifies  into  a  soft  yellowish-brown  mass, 
possessing  a  somewhat  disagreeable  odor. 

The  recovered  grease  is  largely  used  for  smearing  the  coats  of  sheep  before  the  win- 
ter. It  is  used  for  lubricating  railway  axles  and  heavy  parts  of  machinery.  It  is  also 
used  to  some  extent,  mixed  with  other  fatty  matters,  in  the  manufacture  of  inferior 
qualities  of  soap.  It  is,  however,  ill  adapted  for  this  purpose,  since  it  contains  sub- 
stances which  are  not  saponified  by  caustic  alkalies.  The  soap  also  possesses  the  dis- 
agreeable odor  peculiar  to  recovered  grease. 

There  are  no  special  regulations  in  this  country  governing  the  removal  or  the  dis- 
posal of  the  waste  liquors  from  wool  scouring,  but  any  nuisance  arising  therefrom 
would  be  treated  under  the  ordinary  rivers-pollution  act,  1876  (39  and  40  Vic.,c.  75). 


REPORT  OF  CONSUL  UNDERWOOD. 

In  scouring  wool  the  patent  alkali  of  Messrs.  Brunner,  Moud  &  Co., 
of  Northwick,  Cheshire,  is  universally  employed.*  In  the  woolen  mills 
and  dye-houses  wooden  tanks  are  set,  into  which  the  scourings  are  run. 
By  adding  sulphuric  acid  the  grease  is  raised  to  the  surface,  after  which 
it  is  skimmed  off  with  ladles  and  put  into  drainers  or  filter-beds,  in  order 
to  free  it  as  far  as  possible  from  water.  The  substance  that  remains 
alter  the  water  is  drained  off  is  called  "magma."  The  process  thus  far 
is  performed  at  the  mill  or  dye-house,  and  the  magma  is  put  into  casks 
and  removed  to  the  oil  works  for  treatment.  As  to  quantity,  it  may  be 
observed  that  a  tank  of  tLe  soap  water  or  scourings  containing  300  or 
500  gallons  will  yield  from  25  to  100  pounds  of  magma. 

At  the  oil  works  the  magma  is  boiled  and  treated  again  with  sulphu- 
ric acid,  after  which  it  is  put  in  bags  and  submitted  to  hydraulic  pres- 
sure, when  it  comes  out  as  a  black  oil. 

This  black  oil  is  purified  as  carefully  as  possible,  so  that  no  water  or 
impurities  may  remain,  and  is  distilled  by  superheated  steam.  After 
coming  from  the  retorts  and  in  a  hot  state  it  is  put  in  refrigerators  and 
then  in  tubs.  It  is  now  known  as  "  fatty  acid."  The  distillation  is 
then  repeated.  There  remains  in  the  stills  a  black  substance  which  has 
to  be  blown  out  by  steam,  and  which  is  called  "pitch,"  or  "hot  neck 
grease,"  and  is  used  as  a  lubricator  for  journals  in  rolling  mills. 

The  fatty  acid  is  allowed  to  remain  in  the  tubs  until  it  hardens  into 
a  solid,  when  it  is  broken,  placed  in  bags,  and  again  submitted  to  pres- 
sure. The  fluid  oil  is  then  considered  finished,  and  is  called  "  cloth 
oil,"  or  "wool  oil,"  used  by  wool-spinners.  The  residue  in  the  bags  is 
also  a  finished  article,  called  "  stearinej"  and  is  used  for  making  candles, 
tapers,  and  matches. 

It  is  said  that  unless  the  wool  contains  a  great  deal  of  grease  the 
process  above  described  scarcely  pays  expenses. 

*  Analysis  of  Bruuner,  Moud  &  Co.'s  pure  alkali : 

Carbonate  of  soda 98.  90 

Chloride  of  sodium 50 

Sulphate  of  soda 18 

Carbonate  of  lime 23 

Carbonate  of  magnesia 14 

Alumina 01 

Peroxide  of  iron 003 

Silica  01 

Carbon 001 

99. 974 


8  SCOURING  OF  WOOL. 

POLLUTION  OF  STREAMS. 

The  regulations  to  prevent  the  pollution  of  rivers  are  contained  in 
the  act  of  39  and  40  Viet.,  ch.  75,  passed  August  15, 1876,  of  which  the 
title  is  "  The  rivers  pollution  prevention  act." 

This  act  prohibits  putting  solid  matters  into  streams  and  the  drainage 
of  sewers  into  streams,  also  drainage  from  manufactories  and  mines. 
It  recognizes  the  authority  of  local  government  boards,  and  prescribes 
the  maunerof  making  complaints  and  of  hearing  both  parties  interested. 
Offenses  may  be  restrained  by  summary  order  of  county  courts.  An 
appeal  lies  to  the  high  court  of  justice.  The  opinion  of  the  court  is 
based  upon  the  certificate  granted  by  an  inspector  of  proper  qualifica- 
tions, appointed  for  the  purpose  of  the  act  by  the  local  government 
board.  The  certificate  states  that  the  means  used  for  rendering  harm- 
less any  sewage  matter,  or  any  poisonous  or  polluting  solid  or  liquid 
matters,  are  the  best  or  only  practicable  means  available  in  the  par- 
ticular case. 

FEANCIS  H.  UNDERWOOD, 

Consul. 

UNITED  STATES  CONSULATE, 

Glasgow,  December  7,  1885. 


The  following  extracts  are  taken  from  a  report  of  Dr.  Alexander 
Crum  Brown,  professor  of  chemistry  in  the  University  of  Edinburgh, 
made  in  a  case  arising  under  the  rivers-pollution  act: 

The  waste  produced  in  the  mills,  &c.,  which  by  its  escape  into  the  Gala  may  cause 
pollution  of  that  stream  and  of  the  river  Tweed,  may  be  conveniently  classified  thus: 

(A)  solid  refuse;  (1)  the  so-called  "willie  dust,"  which  consists  of  dry  dust  sepa- 
rated from  the  wool  in  the  first  process  of  cleaning  ;  (2)  the  chips  or  powder  of  dye- 
woods  from  which  the  dye  has  been  extracted  by  boiling  in  bags.  (B)  liquid  refuse; 
(1)  soapy  liquids  from  the  scouring  of  wool,  yarn,  or  cloth;  (2)  spent  dye-liquor,  con- 
taining in  suspension  powder  of  dye-woods,  when  the  dye-wood  has  not  been  inclosed 
in  bags,  and  in  solution  unexhausted  dye.  *  *  * 

The  solid  refuse  (A)  is  not  now  allowed  to  enter  the  Gala.  In  most  of  the  works 
it  is  mixed  with  ashes  and  with  soil  from  the  privies,  and  disposed  of  as  manure,  or 
otherwise  removed. 

The  liquid  refuse  (B)  is,  at  most  of  the  mills,  subjected  to  a  certain  amount  of  puri- 
fication before  being  discharged.  We  shall  describe  these  processes  of  purification  as 
they  are  carried  out  at  those  mills  where  the  arrangements  are  most  suitable  for  the 
purpose.  *  *  * 

Soapy  liquids. — These  may  be  conveniently  divided  into  (a)  liquid  resulting  from 
scouring  yarn  and  cloth  with  soap  and  soda.  As  the  yarn  and  cloth  are  compara- 
tively clean  to  begin  with,  this  liquid  is  essentially  a  solution  of  soap.  (6)  Liquidre- 
aulting  from  scouring  wool  with  soap  and  soda.  As  the  wool  is  by  no  means  clean 
to  begin  with,  this  liquid  contains,  besides  a  solution  of  soap,  impurities,  soluble  and 
insoluble,  derived  from  the  wool.  In  some  of  the  works  the  wool  is  scoured  with 
the  soapy  liquid  a  derived  from  the  yarn  and  cloth  scouring,  and  thus  the  total  quan- 
tity of  soapy  liquid  is  diminished.  The  soapy  liquid  a  is  subjected  at  once,  and  the 
liquid  b  after  allowing  the  suspended  impurities  to  settle,  to  a  process  called  the 
"magma"  process.  This  consists  in  treating  it  with  sulphuric  acid,  which  decom- 
poses the  soap,  forming  sulphate  of  soda,  and  setting  free  the  fatty  acids.  These  being 
insoluble  in  water,  form  a  scum  on  the  surface  of  the  liquid  and  can  thus  be  sepa- 
rated. This  scum  or  magma  is  collected  and  sold.  This  process  is  a  profitable  one 
in  the  case  of  the  purer  soapy  liquid  a.  In  the  case  of  the  liquid  from  the  wool 
scouring  the  magma  is  of  less  value,  and  its  separation  from  the  watery  liquid  is  less 
perfect.  The  watery  liquid  from  which  the  magma  has  been  removed  is  in  no  case 
perfectly  clear,  and  is  slightly  acid  from  excess  of  sulphuric  acid.  This  process 
eftects  a  very  decided  improvement,  but  leaves  the  liquid  stfll  impure  and  unfit  to 
be  run  into  the  river.  *  *  * 

Successive  addition  of  alumina  (or  of  red  oxide  of  iron)  and  iron  removes,  as  in- 
soluble lime  and  alumina  compounds,  by  far  the  greater  part  of  the  impurities  dis- 
solved in  the  effluent  from  the  magma  process. 


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